Perforating gun

ABSTRACT

The invention relates to the field of oil and gas production. A perforating gun comprises a single-piece housing containing cavities perpendicular to its longitudinal axis, said cavities being formed directly in the material of the housing of the perforating gun. The following individually manufactured, conjoined structural parts of a shaped charge are hermetically installed directly in the cavities: an outer cap of the shaped charge; a hermetic seal in the form of a ring or gasket; a charge cavity; and a primary explosive pellet. Also disposed in the housing are: a detonation transmission amplifier; a sealing ring; a detonating cord; and a plug with a groove. A detonating cord is connected to each charge, said detonating cord being disposed in a channel formed along the outer surface of the housing and being ballistically connected via an opening to the pellet in the cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application is a National stage application from PCT application PCT/RU2017/000805 filed on Oct. 31, 2017 which claims priority to Russian patent application RU2016146577 filed Nov. 28, 2016.

FIELD OF INVENTION

The invention relates to the devices for the extraction of minerals from boreholes, namely, to the oil and gas industry and, in particular, perforation of oil and gas wells using shaped-charge perforators designed to make inflow channels of behind-the-casing fluids and gases.

BACKGROUND

A shaped-charge perforator containing a tube and shaped charges placed in it is known (U.S. Pat. No. 4,747,201).

The disadvantage of this family member is its modest manufacturability and complexity of shaped charge placing in the tube holes due to fixing shaped charges in the tube holes with the use of additional clamps.

A shaped-charge perforator is known comprising a body in the form of a pipe in which charges in individual pressurized cases made of a fragile material (glass, ceramics, ceramized glass) are placed with the use of fastening parts (SU 1607476).

The prior art device includes a number of parts that complicate the design and assembly of the perforator. The parts fastening the charge in the body, and pressurized charge cases made of a fragile material can be classified as the above parts. When the perforator is activated, the above listed parts are destroyed and clog the well. The use of individual pressurized cases significantly increases the overall dimensions of the charge that results in increase in the perforator dimensions. Durability (number of operations) of the perforator is not defined that can result in the body breakage during releasing (accident).

A shaped-charge perforator is known comprising a loading tube in the form of a metal pipe with mounting seats in which pressurized shaped charges that have an individual metal case (individual body), a cord and initiating devices are placed. At that, the size of the mounting seat corresponds to the size of the charge case, and the number of the perforator operations is determined by the ratio of the explosive material quantity and characteristics to the set of strength and dimensional characteristics of the pipe which the perforator loading tube is made of (RU70929, prior art).

The disadvantages of the perforators known in the state of the art are due to the following. Charge cases are made individually, mainly from steel, by turning or pressing and their combination. The production is labor-intensive, there is a lot of waste (in the case of turning method up to 70% of the metal turns into chips). Charges for capsule perforators should be pressurized, therefore they are difficult-to-make. It is necessary to manufacture loading tubes which are necessary for charge placing in hollow-carrier perforators. Generally, tubes are made by the method of metal laser cutting. The technological process is very expensive, there is a lot of waste. For the manufacturing of loading tubes of hollow-carrier perforators, tubes from thick-walled (from 7 to 12 mm) pipes of special-purpose costly steels are used. One requires costly precision equipment and the process of turning the special-purpose threads for the couplings ensuring tightness of perforators during application. The use of metal (generally steel) for manufacturing each individual charge case is due to the process of pressing an explosive cartridge into it—only a metal case can bear the necessary efforts. In turn, due to the big total weight of individual charges, for their fastening and lowering into the well, it is necessary to use high-strength metal pipes with couplings (adapters) for hollow-carrier perforators or special fasteners for capsule perforators. The use of a thick-walled pipe in the prior art perforator constructions is due to the fact that it should bear (preserve shape) the explosion pressure of shaped charges inside it, so that it can be removed after releasing. In case of depressurization, as well as due to defects in manufacture or assembly, conventional hollow-carrier perforators fail or, even worse, break which makes it very difficult and sometimes impossible to remove them from the well. Removing partially failed charges from a discharged hollow-carrier perforator is also a complex and time-consuming operation.

The task at which the claimed invention is oriented is to create a design of shaped-charge perforators increasing the efficiency of their application, allowing to simplify their manufacturing, expand the range of technologies and materials applicable for their manufacturing, decrease the consumption of materials and the number of components for their assembly. The proposed design of perforator meets the modern demands for the productivity and safety of their manufacturing, storage, transportation and application. The design provides for the possibility of separate, partial or fully assembled transportation of parts and factory-assembled perforators to the places of their application. The design of the current perforator allows for assembly and disassembly, both at the places of their manufacturing and at the place of their application, with the possibility of reusing components and their safe disposal. If necessary, the design allows increasing the charge density (number of charges per perforator meter).

SUMMARY

The essence of the invention is that the perforator contains a monolithic body with cavities made perpendicular to its longitudinal axis; in each cavity, parts of a shaped (cumulative) charge as well as a protective channel connected through the holes to these cavities are mounted in a tight manner. In the channel, a detonating cord is placed which is ballistically connected through the above holes to the charges wherein each charge cartridge is fixed directly in the body cavity and provided with a liner (shaped charge guide) with an outer cap (lid) installed in it.

Mostly, each shaped charge is provided with a detonation transmission amplifier placed in the body hole made between the shaped charge cavity and the protective channel, closed from the outside with a sealing gasket and notched sleeve.

In particular embodiments of the invention, the cavity with a shaped charge, explosive cartridge and a liner are made with the shape of the mating surfaces of the group: conical, spherical.

In particular embodiments of the invention, the outer cap is in a resting contact upon the body and provided with a flat gasket; in other particular embodiments of the invention, the outer cap of the charge is in a resting contact upon the liner and provided with radial rings of circular section.

In particular embodiments of the invention, the body is made cylindrical or multi-sided from the material of the following groups: metal, ceramics, glass, polymeric material.

In particular embodiments of the invention, the perforator is made composed of several bodies connected in series with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 drawing shows a perforator with a charge, assembled and in pieces, with a sealing gasket,

FIG. 2—a perforator with a charge, assembled and in pieces, with a sealing gland,

FIG. 3—a section view of assembled perforator through charge.

The drawings do not cover and, moreover, do not limit the total scope of the claims of this technical solution, but they are merely supporting information of the particular embodiments of the perforator.

PREFERRED EMBODIMENT OF THE INVENTION

The perforator contains a monolithic (one-piece) body 6 (for example, all-metal, all-plastic, of ceramic material, etc.) for a group or all charges, with cavities 5 that are made directly in it and oriented perpendicular to its longitudinal axis that are made directly in the material of the body 6 of the perforator of appropriate dimensions. In cavities 5, shaped charges are installed: separately-made (according to the “briquette” technology) interconnected structural parts of the shaped charge: the shaped charge cap 1, the sealing gasket—elastic sealing gasket 2 or sealing gland (rings of circular section) 13, the liner 3, the cartridge 4 of the main explosive (explosive cartridge). In addition, the detonation transmission amplifier 7, the sealing elastic sealing gasket 9, the detonating cord (cable) 10 and the notched sleeve (clip) 11 are placed from the diametrically opposite side in the body 6 (opposite to the cavity 5).

The detonating cord 10 placed in the protective channel 12, made on the outer surface of the body 6 and ballistically connected through the holes 8 with the cartridge 4 in the cavity 5, is connected to each charge. The cartridge 4 of explosive substance of each charge is fastened directly in the cavity 5 of the body 6 and provided with the liner 3 mounted on it with the outer cap 1.

The cavity 5 in the body 6 of the perforator, the explosive cartridge 4 and the liner 3 are made with smoothly curved mating surfaces. In particular embodiments of the invention, the cavity 5 in the perforator body 6, the explosive cartridge 4 and the liner 3 can be equivalently made with conic or spherical mating surfaces.

The claimed design of the perforator is implemented in the presence of the ready-made explosive cartridge 4, i.e. the perforator design is based on the use of the ready-made explosive cartridge 4. The cartridge 4 is made of explosive allowing transportation and installation in ready (pressed) condition.

Mostly, each charge is provided with the detonation transmission amplifier 7, placed in the hole 8 of the body 6 between the cavity 5 with the explosive cartridge 4 and the channel 12 with the detonating cord 10, closed from the outside with the sealing gasket 9 and the notched sleeve 11.

Peripherally, the outer cap 1 board (collar) can be in a resting contact upon the body 6 through the sealing gasket 2, in other cases of embodiment, the outer cap 1 end is in a resting contact upon (directly or through an additional gasket that is not marked) on the liner 3 sealed by radial rings —sealing glands 13.

The perforator can be made composed (assembled) of several series-connected sections (bodies 6) forming the casing.

The body 6 can be made cylindrical or multi-sided from the material from the group: metal, ceramics, glass, polymeric material.

The shaped charge is installed in the perforator body 6 in any sequence from opposite sides of diameter of the perforator body 6. On the shaped charge parts side the installation is performed in the following order. The explosion cartridge 4 is inserted into the cavity 5 of the body 6, a conical (or hemispherical) liner 3 is inserted into the internal cone (or hemisphere) of the cartridge 4, the sealing gasket 2 from a resilient (elastic) material is installed over the guide 3, then these parts are pressed and fixed in the cavity 5 of the perforator body 6 with the cap 1 (FIG. 1).

The cap 1 is fixed in the body 6 with a thread or a tight fit (with a preform). If the diameter of the perforator body 6 is significantly greater than the height of the explosive cartridge 4 and liner 3, it is possible to additionally use threaded or V-locking rings (not shown) for fixing in it. In this case, for example, the upper part of the cavity 5 of the body 6 can be made with an internal thread, and the cap 1 with an external thread. The sealing gasket 2 is installed under the stepped board of the cap 1 for sealing. Instead of or in addition to the gasket 2, it is possible to apply self-curing polymeric sealant —gaskets to the mating surfaces of the cap 1.

In other embodiments of the claimed perforator the inner part of the cavity 5 of the body 6 is cylindrical, and explosive cartridge 4 and the guide 3 are fixed in the body with the cap 1 with sealing gaskets 13 (FIG. 2) on its cylindrical part. Ring gaskets (radial rings of circular section) 13 are made of resilient (elastic) material with an outer diameter greater than the internal diameter of the cavity 5 that mates with them. When installing the cap 1 they fix in the compressed state the guide 3 and the cartridge 4, simultaneously sealing them from the external environment.

On the opposite side of the diameter in the through-hole 8 connecting the cavity 5 and the channel 12, the detonation transmission amplifier 7 is placed; on the ledge of the hole connecting the cavity 5 and the channel 12, the sealing gasket 9 is installed which is pressed against the body 6 by the sleeve 11.

The sleeve 10 can be screwed into the thread or pressed into the body 6 of the perforator, preferably, can optionally be sealed with the sealing gasket 9. During the pre-installation the notch of the sleeve 11 is installed coaxially to the channel 12 under the detonating cord 10 in the body 6 of the perforator. The channel 12 in the perforator body 6 has a cross section that is slightly larger than the detonating cord 10, as a result, when the cord 10 is laid there, it provides a recessed position for the protection against the damage from the casing pipe walls during lowering. The channel 12 can be laid on the outer surface of the body 6 both in a spiral and straightforwardly depending on the phasing (angular position) of the charges (parts 1-4) assembled in the perforator body 6.

In this case, the body 6 performs (combines) the functions of the tube, the individual charge case and the general body of the perforator (pipe), thereby eliminating the manufacture of individual charges of the perforator, as such, in special individual cases (i.e. individual metal shells) and/or frames, as well as a number of complex intermediate parts, and the implementation of the relevant assembly operations.

The use of the claimed perforator is made in the usual way for its intended purpose for well perforation.

When charges are initiated using the cord 10, the explosive of the cartridge 4 detonates, generating heat and forming gases under high pressure. The detonation transmission amplifier 7 provides detonation transmission from the detonating cord 10 to the explosive cartridge 4. In the shaped charges, with the detonation of explosives, due to the presence of the guide 3, a directional jet with a high impact concentration is formed, which provides penetration at a considerable depth.

If necessary, the perforator is disassembled in the reverse order, by unscrewing (in a case of a threaded joint) or “prying” the side end (in a case of pressing in) of the cap 1. Parts 2, 3, 4 are extracted manually with a light tapping on the body 6 of the perforator when turning.

As a result of the implementation of the current technical knowledge, the following technical result can be obtained.

1). Reducing the dimensions, mainly the diameter of the perforator body 6 while maintaining the density of charge and weight of the charge cartridge 4. I.e. the charge for a perforator with a diameter of 85-89 mm is placed in the case 6 with a diameter 20 mm less than the usual which allows using more powerful charges in the casing pipes of smaller diameter.

2). Eliminating the need for the following material and labor-intensive processes:

-   -   manufacturing of individual cases of charges, because the body 6         of the perforator is at the same time the charge case;     -   reliability of charge sealing is simplified and enhanced;     -   the manufacturing process of perforators is simplified as it         eliminates the manufacture of individual bodies, loading tubes         and a loading sealed pipe, as well as manufacturing steel sealed         couplings for connecting perforators. If it is necessary to use         couplings for connecting perforators, including metal ones, the         couplings are reduced in dimensions and simplified in regard to         the design;     -   for manufacturing the body 6 of the claimed perforator, an         industrial multi-sided bar or a metal circle of a diameter         corresponding to the perforator is suitable. The process is         implemented by processing on CNC machines, with metal hardening         and applying a protective coating, if necessary. The reduced         weight of the perforator and the absence of necessity for         special sealing of the perforator as a whole allows to simplify         the design and use various materials available for the         manufacture.

3). The weight of the body 6 and the whole perforator is reduced by at least two times, compared to a conventional perforator with charges of the explosive cartridge 4 of the same weight, which will significantly reduce both the direct costs of materials and the indirect costs of transportation, loading and unloading. The design allows, if necessary, to increase the density of charge (the number of charges per perforator meter) or reduce the length of the body with the same number of charges.

4). For the manufacture of the perforator body 6 it is possible to use a variety of available modern materials, for example, a variety of light metals, alloys, ceramics, glass, polymers, which will drastically reduce its weight.

5). Sealing each charge separately in the claimed perforator design allows reducing material consumption and avoiding the use of a thick-walled perforator pipe.

Since in the claimed perforator design each charge is sealed separately, depressurization (failure) of one of them will not result in failure of the others, unlike the well-known hollow-carrier perforators. This will reduce accidents and increase operational safety.

6). For the production of perforators, the technology range can be expanded. In addition to the metalworking technologies used, it is possible to manufacture the body 6 by casting, both under pressure and without, for metal melts, liquid polymers, glass, up to 3D printing from polymers and ceramics.

7). It is possible to manufacture the perforator body 6 from materials that are destroyed in the process of detonation (perforation) without the formation of large fragments, such as glass or ceramics This will allow avoiding the operation of lifting the released perforator and its disposal.

INDUSTRIAL APPLICABILITY

This invention is implemented using universal equipment, widely used in industry. 

What is claimed is:
 1. A perforator, comprising: a monolithic body with cavities made perpendicular to its longitudinal axis; in each cavity, parts of a shaped charge are mounted; a protective channel is positioned along the body; the channel is connect with the cavities via holes; a detonating cord is placed inside the channel; the cord is ballistically connected through the holes to the parts of the charge wherein each charge cartridge of each part of the charge is fixed directly in the body cavity and provided with cumulative funnel with outer cap.
 2. The perforator according to claim 1, wherein each shaped charge is provided with a detonation transmission amplifier placed in the body hole made between the cavity with the shaped charge and the protective channel, the hole being closed from outside with a sealing gasket and a notched sleeve.
 3. The perforator according to claim 1, wherein the cavity with the charge, the explosive cartridge and the liner are made with a shape of mating surfaces of a group: conical, spherical.
 4. The perforator according to claim 1, wherein the outer cap rests on the body and is provided with a flat gasket.
 5. The perforator according to claim 1, wherein the outer cap of the charge is in a resting contact upon the liner and provided with radial rings of circular cross section.
 6. The perforator according to claim 1, wherein its body is made cylindrical or multi-sided from a material from a group: metal, ceramics, glass, polymeric material.
 7. The perforator according to claim 1, wherein it is made composed of several bodies connected in series with each other.
 8. The perforator according to claim 2, wherein the cavity with the charge, the explosive cartridge and the liner are made with a shape of mating surfaces of a group: conical, spherical.
 9. The perforator according to claim 2, wherein the outer cap rests on the body and is provided with a flat gasket.
 10. The perforator according to claim 2, wherein the outer cap of the charge is in a resting contact upon the liner and provided with radial rings of circular cross section.
 11. The perforator according to claim 2, wherein its body is made cylindrical or multi-sided from a material from a group: metal, ceramics, glass, polymeric material.
 12. The perforator according to claim 2, wherein it is made composed of several bodies connected in series with each other. 